The present invention relates to a cable for direct or indirect transmission of electrical signals and/or electrical power, with information transmitters being connected to the cable with a force fit, a positive lock and/or by techniques such as bonding, soldering or welding along the cable.
Today, electrical cables for industrial purposes are technically complex, and accordingly expensive. In order to monitor such cables, for example, for water leaks, sensors for transmitting information are embedded in the cable and are used to detect faulty operating states. Although the basic operation of the cable is important, even greater importance is generally attached to the danger to the overall process in the event of cable faults in technical systems. A cable of the type mentioned initially and having an integrated sensor system is known from DE 195 27 972 A1.
During cable installation, the fitter has until now been provided with markings on the cable, irrespective of whether these are color markings or bar codes, as to the cable type, and which line is which in the respective cable. On the basis of this knowledge and by using the appropriate circuit diagram or wiring diagram, the fitter can then wire up the individual cores in the respective cable. He thus requires not only cable-specific information but also system-specific information, for example in the form of manuals and circuit diagrams.
The object of the present invention is to design a cable of the type mentioned initially such that, even without any extensive written documentation, the fitter is able to obtain all the missing information directly from the cable, by using an evaluation unit. This object is achieved by providing identification transmitters for channel-specific data as information transmitters. The information is transmitted either without wires, inductively or capacitively or by means of electromagnetic waves, or by use of wires from the identification transmitters to at least one evaluation unit. The application as originally filed in German is incorporated herein by reference.
In a preferred embodiment of the present invention, the identification transmitters are supplied with electrical power in series via a line system. In this way, the identification transmitters can be supplied centrally with electrical power at a defined voltage or with a defined current. This is of major importance for safe and reliable operation particularly when the identification transmitters contain technical facilities of relatively major complexity, such as microprocessors. Since the identification transmitters are connected to the cable in a predetermined grid pattern, the grid pattern can be used to deduce the respective cable location. The grid pattern can then either be used incrementally, by which means only length changes can be detected, or it is also possible to obtain information about absolute locations on the cable by means of position coding. Since the identification transmitters are all arranged in the spaces formed between the conductors in the cable, the installation of the identification transmitters does not interfere with the external shape of the cable.
In a further preferred embodiment of the present invention, sensors for detecting cable-internal or cable-external physical measurement variables are also provided, and are included in the information transmission. The option of using sensors for detecting operating states of the cable or environmental variables related to the cable has already been mentioned in the introduction. It is advantageous that this functionality be included without any problems in the information transmission for providing identification. Since the identification transmitters are in the form of integrated electrical modules, possibly with sensors being included, these modules can be produced with extremely small dimensions.
In order to ensure that the invention can also be used with shielded cables, a further preferred embodiment of the present invention provides for the identification transmitters to be located outside the shield. This may either be done by the identification transmitters being integrated in the plastic sheet of the cable. If the identification transmitters are provided within a shielded area, free spaces must be provided, for example in the form of cutouts or upward bends in the shield.